<h1>Mutual defense uncertainty risks NATO deterrence and prompts allied planning for burden sharing and force posture adjustments.</h1> Uncertainty over U.S. commitment to NATO has heightened allied concern about the Alliance's future and collective defense credibility. U.S. rhetoric suggesting closer ties with Russia and questions about mutual defense assurances have prompted European and Canadian planning for burden sharing, force posture adjustments, and insistence that U.S. nuclear and naval assets remain in Europe. Allies are exploring higher defense spending targets and coordinated contingency plans should U.S. forces be reduced or redeployed.